Place pancetta, onions, and garlic in large skillet set over medium heat; cook until pancetta crisps and onions caramelize; add beans and grappa; cook until tender (about 5 minutes); season; remove from heat; reserve (keep warm).

To serve, bring a pot of salted water to a boil; add pasta; cook until al dente; drain in a colander; add pasta to bean mixture; toss to combine; drizzle with oil; season; divide among serving dishes; sprinkle with cheese.